Abstract:
This study is focus on the analysis of dry spell and its impacts of the yields of maize and wheat
crops in Hadiya zone, southern Ethiopia. The study area is geographically located between 7.010
to 7.6o
N and 37.2o
to 38.1o
E and 2307m above sea level. Statistical analysis was made using
coefficient of variation (CV), precipitation concentration index (PCI), standardized anomaly
index (SAI), standardize precipitation index (SPI), Markov chain order one (Instat v+3.36),
Multiple regression model and bias correction methods to assess the climate of study area over
last three decades, predicting future climate and to find out their impact on productivity of
selected crops. Accordingly, the rainfall in the area was characterized by alteration of wet and
dry years. Dry years recorded as low as 60.65% below the long term average. Maize and Wheat
production show considerably relation with the rainfall of main rainy season. Three RCP future
climate scenarios, RCP2.6, RCP4.5 and RCP8.5 of future periods (2015-2100) dynamically
downscaled data were obtained from CORDEX-Africa, and then bias corrected for study area.
The changes in the status of the climate between the baseline period and the three future
scenarios were recognized. The study revealed that in the case of bias correction average annual
rainfall is going to increase by 28.26% and 0.56% in 2020s, for RCP2.6 and RCP8.5 scenarios
respectively, but it will be decreased by 15.5% using RCP4.5 in the same period. Dry spell years
of the baseline period and the future scenarios were identified using SPI (standardized
precipitation index) and used to estimate the impacts on percentage yield losses of maize and
wheat using multiple regression model and INSTAT software v+3.36. The results investigated
that dry spells will become less frequent and more severe for RCP4.5 less frequent and moderate
for both RCP2.6 and RCP8.5 scenarios relative to dry spell of the baseline (1988-2014). The
analysis generally indicated that the occurrence of prolonged dry spell will have higher yield
loss impacts on Maize with the percent loss of 21% in the observed period and 40.6% for the
future. And medium impact on Wheat with the percent loss of 17% in the observed period as
well as 18.7% for the future emission scenarios will be indicated. So that the farmers of the area
should adjust the future farming system in different techniques such as using the small scale
irrigation in the suitable areas, also by using different soil and water management techniques
and by arranging the planting time of selected crops.
